Medicinal Cannabis, Serious Misconduct and Unfair Dismissal: Can I be fired for smoking weed?

The Growing Reality of Cannabis Use in Australian Workplaces

With the legalisation of medicinal cannabis in 2016, more Australians are turning to it as a treatment for chronic health conditions. But while medical professionals are embracing cannabis as a legitimate therapy, many employers still view it through the lens of illicit drug use — often applying outdated, rigid policies that fail to distinguish between lawful and unlawful conduct.

This modern reality makes it increasingly difficult to justify blanket zero-tolerance policies, especially when they treat prescribed medication the same way as illicit substances.

Can You Be Dismissed for Using Medicinal Cannabis?

Yes — but that doesn’t mean your dismissal is fair or lawful.

Employers in safety-sensitive industries have a legal obligation to ensure workers aren’t impaired while on duty. However, a positive THC result doesn’t necessarily prove impairment, nor does it automatically justify dismissal.

Dismissal might be justified if:

• You fail to disclose use of prescribed cannabis when workplace policies require it.

• You work in a safety-critical role, and the employer cannot safely accommodate your medication use.

• You breach a clearly communicated and consistently enforced drug policy.

• You refuse or avoid a required drug test.

But even in these scenarios, the Fair Work Commission often assesses whether the dismissal was harsh, unjust or unreasonable, based on context, risk, disclosure, and procedural fairness.

Recent Case Law: How the Fair Work Commission Is Deciding Cannabis Dismissals

Adam Mills v Glamorgan Spring Bay Council [2025]

Mr Mills operated heavy machinery and was terminated after a drug test revealed THC. He had told his employer about his medicinal cannabis use, but not that it contained THC. The employer concluded he could no longer perform his duties safely.

The Commission accepted there was a valid reason for dismissal due to safety and disclosure concerns. However, it found the dismissal was harsh given Mr Mills’ personal circumstances, lack of prior issues, and willingness to stop using cannabis. He was reinstated with 31 weeks’ backpay.

Sheldon Haigh v Platinum Blasting Services [2023]

Mr Haigh, who handled explosives, initially disclosed his use of medicinal cannabis but failed to update his employer when he resumed use. He passed all drug tests and limited use to off-site periods.

The FWC still upheld his dismissal due to his failure to comply with disclosure obligations, given the high-risk nature of his work and the company’s clear, repeated warnings.

Gauci v DP World Brisbane Pty Ltd [2024]

Mr Gauci used prescribed cannabis to manage a mental health condition but did not notify his employer. He failed a drug test with THC levels ten times over the company’s threshold. Because his work was safety-critical and the policy required disclosure, the FWC found dismissal was lawful.

Candido v Scalzo Trading Co Pty Ltd [2024]

After being told to take a drug test, Mr Candido left the worksite, claiming a personal emergency. The Commission concluded he was attempting to avoid the test, and his dismissal was found to be a reasonable and proportionate response, especially given his prior warning.

Millar v FQM Australia Nickel Pty Ltd [2022]

Mr Millar was dismissed after he could not pass a urine drug test while using prescribed cannabis to treat Crohn’s disease. He claimed disability discrimination, arguing the company failed to consider reasonable adjustments.

The Federal Court found the employer had not sufficiently explored accommodations. Mr Millar was temporarily reinstated while his Human Rights Commission complaint is resolved.

Sydney Trains v Hilder [2020] FWCFB 1373

This key Full Bench Fair Work Commission decision offers a contrasting view. Mr Hilder was dismissed for testing positive to THC, in breach of Sydney Trains’ zero-tolerance policy. However, he had been prescribed medicinal cannabis, and the Commission found that the employer had not followed its own disciplinary procedures, which required consideration of mitigating factors.

The Commission found the dismissal was unfair, because:

• The policy failed to distinguish between prescribed and illicit cannabis use.

• The employer did not consider whether the employee was actually impaired.

• The disciplinary process lacked procedural fairness.

This case remains a leading authority on why a rigid, inflexible approach to medicinal cannabis can lead to unfair dismissal outcomes.

Why a One-Size-Fits-All Policy Doesn’t Work Anymore

Employers can no longer afford to treat all drug use the same. Medicinal cannabis, like any other prescription medication, can have side effects — but unlike alcohol or other substances, THC can remain in the body long after impairment has passed.

There’s currently no standard test for impairment, and standard drug testing:

• Urine tests detect use long after the effects have worn off.

• Oral fluid testing is more closely aligned with recent use and potential impairment.

Unions and employee advocates are increasingly calling for oral fluid testing because it reduces the risk of disciplining employees for off-duty conduct that poses no risk at work.

The Legal Framework: Further Explored

Work Health and Safety (WHS)

Employers must keep workplaces safe. If medicinal cannabis could impair an employee in a safety-critical role, the risk must be assessed and managed. That said, dismissal should not be the first or only response.

Disability Discrimination

Medicinal cannabis is often prescribed for a recognised disability. Employers must make reasonable adjustments unless doing so would cause unjustifiable hardship. Automatically dismissing a worker because they use cannabis may breach federal or state discrimination laws.

Privacy Obligations

Medical information is private. However, if your role carries health and safety responsibilities, disclosure of impairing medications may be required. Employers must handle this information lawfully, respectfully, and securely.

Enterprise Agreements and Consultation

Some workplaces have enterprise agreements that regulate drug testing and disciplinary action. Employers must follow consultation procedures when changing drug and alcohol policies or testing practices. A failure to do so could render a dismissal procedurally unfair.

Employee Checklist: Protect Your Rights If You Use Medicinal Cannabis

If you are prescribed medicinal cannabis and worried about your job, here’s what you should do:

• Review your employer’s drug and alcohol policy to understand disclosure obligations.

• Notify your employer if you are required to under policy or contract.

• Request reasonable adjustments where appropriate.

• Keep evidence from your doctor about your ability to perform your role safely.

• Act quickly if you are dismissed — you have only 21 days to lodge an unfair dismissal application.

Cannabis-Related Dismissals Must Be Fair, Lawful and Context-Specific

The use of medicinal cannabis is rising, and so is the body of case law around it. Dismissals are no longer being judged solely on drug test results — but on context, fairness, and the employee’s rights under privacy, WHS, and anti-discrimination laws.

The most recent decisions from the Fair Work Commission show that while employees must take their obligations seriously — especially around disclosure — employers must also be reasonable, consultative and fair in how they respond.

If you’ve been dismissed due to cannabis use, and you believe the decision was harsh, unjust or unreasonable, you may have grounds for a successful unfair dismissal claim.